User's Guide

Chapter 9 Network Address Translation (NAT)
LTE Series User’s Guide
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Figure 83 Trigger Port Forwarding Process: Example
1 Jane requests a file from the Real Audio server (port 7070).
2 Port 7070 is a “trigger” port and causes the Zyxel Device to record Jane’s computer IP address. The Zyxel
Device associates Jane's computer IP address with the "open" port range of 6970-7170.
3 The Real Audio server responds using a port number ranging between 6970-7170.
4 The Zyxel Device forwards the traffic to Jane’s computer IP address.
5 Only Jane can connect to the Real Audio server until the connection is closed or times out. The Zyxel
Device times out in three minutes with UDP (User Datagram Protocol) or two hours with TCP/IP (Transfer
Control Protocol/Internet Protocol).
Click Network Setting > NAT > Port Triggering to open the following screen. Use this screen to view your
Zyxel Device’s trigger port settings.
Note: TCP port 7547 is reserved for system use.
Note: The sum of trigger ports in all rules must be less than 1000 and every open port range
must be less than 1000. When the protocol is TCP/UDP, the ports are counted twice.
Figure 84 Network Setting > NAT > Port Triggering